Libya's El-Sharara oilfield, the country's largest, was forced to stop production on Tuesday as an armed group stormed the facility, the National Oil Corporation (NOC) said.
"This is a criminal act that amounts to treachery against the Libyan people and national economy as the closure will cause the public treasury more losses," NOC said in a statement.
On Sunday, El-Sharara oilfield resumed production after a months-long hiatus.
On Jan. 17, warlord Khalifa Haftar's militia closed Az-Zuwaytinah port, claiming that oil revenues were being used by the internationally-recognized Government of National Accord.
El-Sharara oilfield produces more than 300,000 barrels of crude oil per day, forming roughly one third of the oil-rich country's production.
Libya holds Africa’s largest crude reserves, but nine years of conflict and violence in the country since the 2011 ouster of ruler Muammar Gaddafi have hobbled the production and exports.
Libya's internationally recognized government has been under attack by Haftar's forces since April 2019, with more than 1,000 killed in the violence.
The government launched Operation Peace Storm in March to counter attacks on the capital and recently regained strategic locations, including the Al-Watiya airbase and Tarhuna, which is viewed as a significant blow to Haftar's forces.